The invention relates to a motorized joint with two pivot connections, and a humanoid robot which implements the joint. The invention is particularly useful in the production of humanoid robots, the ergonomics of which it is wished to improve.
Robots of this type are equipped with numerous joints which make it possible to move different parts of the body of the robot, such as the head or the limbs. Certain joints of the human body, such as the shoulder, the elbow or the neck can be reproduced in a robot by means of a joint comprising two pivot connections, which are also known as double pivot connections. More specifically, the outlet from the first pivot connection forms the inlet to the second pivot connection. For example, at the elbow, the forearm is articulated relative to the arm such as to permit a first rotation of the forearm around an axis according to which the forearm extends, as well as a second rotation around an axis which is at right-angles to the first axis. In other words, the forearm has two degrees of freedom in rotation relative to the arm.
In a robot, the joints are motorized for example by means of rotary electric motors, which each make it possible to control a degree of freedom in rotation. In a joint with two axes at right-angles, as previously described, it is therefore necessary to have two motors, which each control a rotation. In order to create this joint, it is possible to align the motors with the respective axes of rotation. This arrangement is simple to implement, but in the case of the elbow for example, one of the motors must project in relation to the joint. This protuberance impedes certain movements of the robot.
In addition, in order for the robot to be able to place its arms along its body, the protuberances formed by the motors at the elbows must extend towards the exterior of the body. The protuberances are placed symmetrically relative to a vertical axis which forms the vertebral column of the robot. This arrangement requires the joints to be symmetrical also. The joints cannot be identical, which therefore reduces the standardization of the mechanical parts which constitute the robot.
The object of the invention is to eliminate some or all of these problems, by dispensing with the protuberance necessitated by the motor. In general, the invention makes it possible to improve the compactness of joints comprising two pivot connections.
For this purpose, the subject of the invention is a joint comprising two pivot connections, the axes of which are not parallel, a first motor which drives a first one of the two pivot connections by means of a first speed reducer, and a second motor which drives a second one of the two pivot connections by means of a second speed reducer, characterized in that one of the two reducers comprises a bevel gear between the motor and the pivot connection which are associated by this reducer.